Mud diverting kelly saver sub

ABSTRACT

A sub is provided having a skirt extending down from the pin upset end so as to provide a concentric deflecting surface around the pin. When the kelly joint is unscrewed from the drilling string box, mud from the joint escapes upwardly through the annular space defined between the pin and box threads. The skirt functions to alter the direction of movement of the mud spray and directs it downward to the rotary table so that it will be returned to the rig mud system.

United/StatesPatent 11-91 11] 3,869,150 Brown Mar. 4, 1975 [54] MUD DIVERIINQKELLY VE UB 2,318,466 5/1923 Cooper'l ..5 l3636/8l 93 2 M 2 3 X [76] Inventor: William Henry Brown, 13055-149 30675 12/19 8 St., Edmonton, Alberta, Canada FOREIGN PATENTS OR APPLICATIONS F 1 178,241 9/1953 ALISIIIQ 285/286 [21] Appl" 333407 Primary E.raminer-Dave W. Arolla Attorney, Agent, or Firm-Ernest Peter Johnson [52] [1.8. CI 285/13, 166/81, 166/242,

285/302, 285/333 [57] ABSTRACT ['51] Int. Cl. F16] 55/00. [581' Field ofSearch 175/321, 320; 166/242, T i a 5km *T g 166/81; 2s5/333,334, 13, 14, 45, 171, 286, t e P upset as P e a l' 331 302 403/1 18 343 flectlng surface around the PIIL WIheII the kelly jOlIlt ls unscrewed from the drllllng strlng box, mud from the joint escapes upwardly through the annular space de- [56] References Clted fined between the pin and box threads. The skirt func- UNITED STATES PATENTS tions to alter the direction of movement of the mud 1,030,387 6/l9l2 Critton 285/333 X spray and directs it downward to the rotary table so ghllders a 285/171 x that it will be returned to the rig mud system. UI'I'IS 2.163. 12 6/l939 Reddick 285/12 3 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to a sub for use with the kelly joint of a drilling string.

A kelly joint is a length of pipe-of square cross section which is attached to the upper end of a drilling string used in oil field'drilling operations. The joint extends through a square opening in the rotary table of the rig using the string. When the table is rotated by the rig mechanism, this rotation is transmitted through the kelly joint to the drilling string.

When the drilling string is drilled down so that the greatest partof the kelly joint is buried beneath the rotary table, it is necessary to: (1) pull the string back up so that the kelly joint is above the rotary table; (2) disconnect the kelly joint; (3) add a new joint of drill pipe to the upper end of the string; and (4) connect the kelly joint with the upper end of the newly added joint so that the system is ready to resume drilling.

When the kelly joint is disconnected from the string to allow a new joint of drill pipe to be added, the drilling mud within the joint sprays out over the rig floor. More particularly, as the pin of the kelly joint is screwed out of the threaded top box of the drilling string, the mud is forced, by hydraulic head pressure, through the narrow annular passage defined between the two threads and sprays upwardly and outwardly.

In the past, drilling mud was inexpensive and could easily be washed off the rig floor. However, in recent years drilling rigs have been operating in cold climates, such as the Arctic, where water and drilling mud are very expensive to provide.

SUMMARY OF THE INVENTION It has occurred to me that substantial savings in drilling costs could be obtained if the drilling mud from the kelly joint were automatically returned to the rig mud system rather than being sprayed around on the rig floor and the like. What is required, therefore, is a means for re-directing the spray of kelly joint mud downwardly, as it leaves the annular space between the threads, so that it will flow down through the'rotary table and into the drilling nipple located beneath it. In this manner, the mud is returned to the mud system of the rig and is not lost. The means should form part of the drilling string assembly so that the re-directing of the mud will occur automatically without any timeconsuming actions on the part of the crew.DESCRIP- TION OF THE DRAWING FIG. 1 is a side view, in section, showing the sub at- I tached to a kelly joint and being disconnected from the drilling string: the path taken by the drilling mud as it escapes from the kelly joint as shown by arrows.

FIG. 2 is a side view, partly in section, showing an alternative embodiment of the invention in the'upper position;

FIG. 3 is a side view, partly in section, showing the assembly of FIG. 2 in the mud-diverting position.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawing, the invention comprises a kelly saver sub 1 having a threaded box 2 and pin at the upper and lower upset ends respectively. The lower upset end 4 is counterbored to provide a peripheral surface 5 to which is secured the tubular member 6. The member 6 extends below the pin shoulder 7,

preferably to a point intermediate the ends of the pin 3.

By way of example, I provide a saver sub having a pin upset end O.D. of 6 inch with a 4 inch long pin tapered from 4 51/64 inches to 3 51/64 inches. The upset end is counterbored for a length of l inches to-a 6 Vs inch OD. The tubular member is 4 inches long and one-fourth inch thick, and has an CD. of 6 inch and an ID. of 6 Vs inch. When welded to the pin upset end, the tubular member extends 2 7a inches beneath the pin shoulder and is adapted to fit over a. drill pipe box 8 having a 6 inch 0D.

In use, when the kelly joint 9 and saver sub 1 are backed out'of and separated slightly from the drill pipe box 8, the drilling mud in the kelly joint 9 escapes through the annular space 11. On striking the inner deflecting surface 12 of the tubular member 6, the upward direction of movement of the mud is changed and it follows a downward path to the rotary table (not shown). On passing through the openings in the rotary table, the mud drops into the flow nipple (not shown) beneath the rotary table and joins the mud stream returning therethrough to the rigs mud tanks.

The upset tool joint of drill pipe 61 is usually provided with a built-up, circumferential band 50 of hardfacing. The band 50 is about 3 inches in width, leaving about 7 inches between its top edge and the top edge of the tool joint 61. Since the mud-diverting tubular member 58 extends 2 inches down over the tool joint 61 when the saver sub is made up with it, this leaves only 4 inches between the hard-facing band 50 and the tubular member 58. When a rig; tong is thrown onto this 4 56 inch thick section to break the threaded connection, part of the tong tends to work on the hardfacing band 50. The tong dies are frequently broken when this occurs.

In a preferred embodiment of the invention, a guide slot 52 is cut in the body member 53 of the saver sub 54. The guide slot 52 has a vertical section 55 and top and bottom horizontal sections 56, 57.

The tubular member 58 is slidably mounted on the body member 53 for longitudinal movement between the upper and lower positions illustrated in FIG. 2 and 3. A lug 59 protrudes inwardly, from the tubular member 58, and extends into the guide slot 52. The slot 52 and lug 59 cooperate to guide the sliding movement of the tubular member 58. As shown in FIG. 2, in the upper position the lug 59 is lockedin the slot section 56 and the lower end of the tubular member 58 is located above or adjacent the upper end of the pin 60. In the lower position, the tubular member 58 has dropped down and extends over at least part of the pin 60.

When breaking the threaded connection between the saver sub 54 and the drill pipe 61, the tubular member 58 is locked in the upper'position. When the saver sub 54 is to be spun out, the tubular member 58 is turned manually, to bring the lug 59 into the slot vertical section 55, and then dropped to the lower mud-diverting position. The seal ring 62, mounted in a groove cut in the outer face of body member 53 adjacent is lower end, functions to prevent mud leaking upwardly past the end of the tubular member 58.

The advantage to be derived from the use of the invention is that the mud previously lost from the kelly joint on unscrewing it is automatically returned to the mud system without any action on the part of the drilling crew.

What is claimed is:

1. In a sub for use with the kelly joint of a drilling string, said sub having a body member comprising at its 5 lower end a shoulder and a tapered threaded pin of reduced diameter extending downward from the shoulder,

the improvement which comprises:

an imperforate circumferentially continuous tubular member concentric with the body member; and means permanently attaching said tubular member to said body member, whereby said tubular member forms a part of said sub, said tubular member extending below the shoulder and overlapping at least a portion of the threads to provide a deflecting surface for escaping drilling mud.

2. The improvement as set forth in claim 1 wherein:

the tubular member extends down to a point intermediate the ends of the pin. 3. The sub as set forth in claim 1 wherein:

the tubular member is slidably mounted on the body member;

one of the members has a guide slot formed in its body, said guide slot having a vertical section and a horizontal section at the upper end thereof;

and the other member has a protruding lug which extends into the guide slot and cooperates therewith to guide the tubular member as it is shifted along the body member between the upper position, wherein the lug is locked in the horizontal section and the lower end of the tubular member is located adjacent the upper end of the threaded pin, and a lower position wherein the tubular member. ex-

tends down over at least part of the threaded pin. 

1. In a sub for use with the kelly Joint of a drilling string, said sub having a body member comprising at its lower end a shoulder and a tapered threaded pin of reduced diameter extending downward from the shoulder, the improvement which comprises: an imperforate circumferentially continuous tubular member concentric with the body member; and means permanently attaching said tubular member to said body member, whereby said tubular member forms a part of said sub, said tubular member extending below the shoulder and overlapping at least a portion of the threads to provide a deflecting surface for escaping drilling mud.
 2. The improvement as set forth in claim 1 wherein: the tubular member extends down to a point intermediate the ends of the pin.
 3. The sub as set forth in claim 1 wherein: the tubular member is slidably mounted on the body member; one of the members has a guide slot formed in its body, said guide slot having a vertical section and a horizontal section at the upper end thereof; and the other member has a protruding lug which extends into the guide slot and cooperates therewith to guide the tubular member as it is shifted along the body member between the upper position, wherein the lug is locked in the horizontal section and the lower end of the tubular member is located adjacent the upper end of the threaded pin, and a lower position wherein the tubular member extends down over at least part of the threaded pin. 